To make the custard for the ice cream, dump all ingredients in a saucepan and whisk to combine.
Cook on low-medium heat, stirring constantly, until the mixture is thick enough to coat the back of a spoon. This means if you stick a spoon in the mixture and pull it back out, you can wipe a finger down the back of the spoon and it will leave a clear mark where the custard used to be. Be careful not to overcook or you will have lumpy scrambled eggs in your ice cream.
Strain the mixture using a fine mesh sieve to get all the tea leaves out. Chill in the fridge at least a few hours or until the ice cream base is completely cold. I leave mine overnight. Meanwhile, make sure your ice cream maker is ready.
When your ice cream mixture is cooled, churn in your ice cream maker according to your machine's instructions. Mine took about 25 minutes.
Eat immediately at soft serve consistency, or put in freezer to harden to scoopable ice cream texture.